The objective of this study is to measure the impact of newborn intensive care on a geographically defined population, the newborns of New York City. The primary outcome of interest is mortality, from late fetal to infant, with particular emphasis on neonatal mortality and its subdivisions. Using New York City live birth, infant death and fetal death certificates, we will examine mortality within birthweight categories in several different ways for each of three levels of neonatal care. This analysis will proceed both cross-sectionally and over time. We will also attempt to correlate characteristics of hospital functioning with outcome, and analyze the contribution of infant transport to the overall effect of new born intensive care. We hope as a result to generate information that will provide a sound basis for perinatal planning and that will be a first step toward understanding the interaction between neonatal interventions and brain-damaging conditions of childhood.